Apart from the debate that exists about whether eating eggs is bad for your health (which we already tell you that it is not), it is interesting to know why the world of fitness has decided that it is better to consume more egg whites than whole eggs. Does it increase muscle growth? Isn't it better to take eggs with yolk to increase nutrients?
If you are a regular at the gym or training with company, you will have been told about the importance of post-workout meal. which must contain to a greater extent proteins and carbohydrates fast digestion, but very little fat.
This type of food is recommended to contain these characteristics so that amino acids enter the blood much faster, protein synthesis is increased and the muscle growth. Fat is a nutrient that takes longer to digest, so it doesn't usually give it a great post-workout role.
But the obsession with segmenting nutrients can make us fall into error. They are not only fats, carbohydrates or proteins, there are many micronutrients necessary for a good recovery. That is, if we avoid fat after training, it could be counterproductive.
What happens to whole eggs? Why is there suspicion? Many people think of eggs as a protein source based on the whites, so they throw away the yolks without remorse.
Instead, the University of Toronto has conducted a study to determine if whole eggs are better than egg whites for muscle growth.
How does the study was realized?
There were 10 young people, about 21 years old, who underwent this investigation. They had to do a leg training which consisted of 4 series of extensions and presses with 10 repetitions each.
Then the ten boys were divided into two groups:
- 1 Group: ate 3 whole eggs post-workout
- 2 Group: they ate an amount equivalent to 18g of protein from egg whites, post-workout as well.
And with the volunteers split, they performed various methods to learn how "anabolic" both foods were:
- They mixed the eggs with compounds called "isotope tracers«. These allowed us to see how much protein from the eggs went directly to the muscle tissue, compared to the rest of the organs.
- They measured how quickly each food affected levels of leucine, and how long they remained elevated after each meal. Leucine is a key amino acid in protein synthesis, and foods that maintain a high blood level are considered better for muscle growth.
- They pricked their legs to remove a small piece of muscle tissue. They then examined them to directly measure how it was influencing protein synthesis in muscle fibers.
The scientists were conducting tests for 5 hours after finishing the training. All the youngsters who ate whole eggs the first time went on to eat egg whites the second time, and vice versa. Thus, a result based on the average was not given, but in a more specific way, crossing data.
What did they conclude?
In the graph on the left you can see how much protein synthesis was happening in the muscle fibers. Protein synthesis levels increase in many organs of the body after eating, but in this case we wanted to know if they increased or not.
In the one on the right we can see that protein synthesis in the body was more or less the same in both groups. But if you look at muscle protein synthesis, people who ate whole eggs had a 42% more protein synthesis than people who only drank whites.
Actually, the scientists themselves were surprised by the result and do not know how to give an explanation for sure. Even so, they commented on what the causes could be:
The extra calories from whole eggs will increase protein synthesis.
Egg whites contain 73 calories, compared to 226 for whole eggs. Interestingly, eating more calories keeps protein synthesis up, although this is probably not the main reason.
A similar study found that drinking the same number of calories from whole milk as from skim milk caused a greater increase in protein synthesis, despite eating less protein.
It's true that calories matter, but the number we eat at a single meal isn't nearly as important as your intake throughout the day when trying to build muscle.
The cholesterol content of the yolks increases protein synthesis
There are studies that show that people who consume more cholesterol build more muscle than those who take less. Cholesterol influences the production of testosterone and other anabolic hormones, so it is very logical that it is part of that difference compared to whites.
Some of the compounds in the buds affect gene expression
Egg yolks also contain micronutrients such as vitamins, minerals, and unique fatty acids, which can promote muscle growth.
There was a study that showed that both whole eggs and yolks caused changes in genes related to muscle growth.
So are whole eggs better for muscle growth?
At first glance we might say yes, but short-term levels of protein synthesis do not translate into increased muscle growth in the long term.
This study shows that you don't need to have a low-fat post-workout meal. Leucine levels increased slightly after eating egg whites, so the egg whites were digested a bit faster, but that does not imply that there was increased protein synthesis.
